"Fortunately for us, our public safety officers and university officials have trained many of us for active shooter situations," Don Allan Mitchell, an English professor, wrote in a Facebook message to The Associated Press. "Many students are locked-down in classrooms, and professors and staff members are telling them the protocol. Plus, we are all texting and Facebooking each other to make sure we are safe."

He said police helicopters were in the air, and officers were sweeping buildings.

However, another English professor, Bill Hays, said the university did a poor job of communicating with faculty, staff and students about the emergency situation.

"It's really frustrating because there is no campus-wide updating from a central command center. Everything we're getting is just rumours," Mr Hays said in a phone call from his office in Keithley Hall, across the street from the shooting site.